The issue of breastfeeding in the workplace is not only related to the protection of the rights and interests of female workers and the physical and mental health of mothers and infants, but also has realistic and positive research value on how to balance the tension between the employment pressure of enterprises and the protection of the rights and interests of female workers after the implementation of the "three-child policy" in China. The study analyses the factors affecting breastfeeding in the workplace at three levels: individual, institutional and social structure levels. The research results show that, at the individual level, education has an impact on the overall duration of breastfeeding and the duration of continued breastfeeding after returning to work; at the organizational level, clear regulations are an effective safeguard of fertility rights and interests; at the social structure level, with the increase of maternity leave, its impact on the extension of breastfeeding time shows a diminishing marginal benefi t. Therefore, a scientifi c and reasonable maternity leave system and the construction of a mother-infant friendly society are of special signifi cance to promote breastfeeding. The study suggests that the reasonable sharing of fertility costs needs to be addressed at the macro level in order to stimulate enterprises to implement the initiative of fertility protection policy.